Splicing thermoplastic monofilaments



J 1950 F. J. GROTEN ETAL 2,514,197

smcmc THERMOPLASTIC MONOFILAMENTS Filed June 20, 1946 v Sheets-Sheet 1 IN v E N T 0 R5 FRANK d.GROTEH AND W! LUAM cJ.NANFELDT ATTORN EYS F. J. GROTEN ETAL SPLICING THERMOPLASTIC MONOFILAMENTS .July 4, 1950 7 Sheets-Sheet 2 Filed June 20. 1946 N v E N TO RS FRANK d. GRQTEN T D L E N M M m L n w ATTORNEYS '7 Sheets-Sheet 3 I N V I. NTO RS FQANKd GEOTEN AND WILLIAM d.NANFELDT s fir yle.

AI'TORN 1Y6 July 4, 1950 F. J. GROTEN ETAL SPLICING THERMOPLASTIC MONOFILAMENTS FiledJune 20, 1946 y 1950 F. J. GROTEN ET AL 2,514,197

SPLICING THERMOPLASTIC MONOFILAMENTS Filed June 20, 1946 7 Sheet's$heet 4 INVENTORS FRANKU. GEOTEN AND WILLlA d.NANFELDT BY w y A TOR CYS y 1950 F. J. GROTEN EIAL 2,514,197

SPLICING THERMOPLASTIC MONOFILAMENTS Filed June 20, 1946 '7 Sheets-Sheet 5 IN VENTORS FRANK d. GROTEN AND WELLEAMJNANFELDT gfgifj' ATTORNKYS 950 F. J. GROTEN ETAL spucmc 'Il-IERMOPLASTIC MONOFILAMENTS '7 Sheets-Sheet 7 Filed June 20, 1946 INVENTORS lam fgNFl-lLDT T O FRANK dgROT'EN WILLIAM Patented July 4, 1950 SPLICING THERMOPLASTIC MONOFILAMEN TS Frank J. Groten, Upper Montclair, N. 1., and William J. Nanfeldt, New Castle, Ind., assignors to The Firestone Tire & Rubber Company, Akron, Ohio, a corporation of Ohio Application June 20, 1946, Serial No. 677,985 3 Claims. (Cl. 15490) This invention relates to the splicing of organic thermoplastic monofllaments, and more particularly to the splicing of oriented organic thermoplastic monofilaments such as polyvinylidene chloride and nylon monofllaments.

As stated, this invention relates to the splicing of organic plastic monofilaments, i. e., wire-like, solid integral plastic strands of substantial cross section, (say 25-400 circular mils cross sectional area) as distinguished from conventional textile threads composed of a number of very fine filaments held together by twist. In the working up of monofilaments into fabrics, screening, etc., considerable difficulty has been encountered in splicing together lengths of these filaments, as for instance where breaks occur, or where it is desired to make up packages, warps, etc., and the lengths of monofilament at hand are too short for the purpose. Knotting of the monofilaments is highly unsatisfactory; the mechanical strength of the knotted section is undesirably low; the knots are very prone to come untied during manufacturing operations, particularly in the warp, which is repeatedly flexed during weaving; and the knots form a particularly objectionable appearance in the final fabric, not encountered with ordinary multifilament fabrics, due to the relatively incompressible nature of the monofilaments. Splicing means, other than knotting, have likewise been found unsatisfactory; for instance, the applicants have conceived the idea of splicing monofllaments together by means of adhesive cements. On account of the smooth, repellent, and non-adhesive character of the monofllament surfaces, however, this procedure was found unsatisfactory.

Accordingly, it is an object of this invention to provide a satisfactory method for splicing plastic monofilaments. 7

Another object is to provide such a method which will result in mechanically strong "splices between lengths of monofllament.

A further object is to provide such a method which will result in splices which will withstand repeated fiexure in any weaving, etc. operations to which they may be subjected, and which will operate smoothly in any textile working machinery employed.

Still another object is to provide splices which will be inconspicuous in the final woven or other fabrics.

A still further object is to secure the foregoing objects in a process which may be expeditiously carried out by relatively unskilled operators by means of relatively simple apparatus.

The above and other objects are secured, in

accordance with this invention, by lapping and welding together the ends of the plastic monofilaments to be joined, the heat for the welding being supplied by subjecting the lapped ends to a high frequency e. m. 15. There result, particularly when conditions are adjusted as more particularly set forth hereinafter, welded joints which approach, in strength, the continuous portions of the monofilaments. The welded joints reliably withstand all usual textile operations and are inconspicuous in the final fabric.

The conditions of field frequency, voltage, etc. applied to monofilaments to weld the same in accordance with this'invention may be quite widely varied. The primary factor is the field frequency, selection of which will approximately determine the values of the other variable conditions to which the monofilaments must be subjected. A

9,0 field frequency of at least megacycles must be employed. Higher frequencies, in the range 150-250 megacycles, are preferable, as they result in stronger and more reliable welds, and also permit of lower voltages and consequent lessened 25 danger of arcing. Still higher frequencies would be desirable, but in most cases would require excessively elaborate equipment.

The voltage of the field to be applied to the monofllaments to be welded is very diflicult to measure, and if measured, would have little signiflcance apart from the geometry of the specific monofllaments and associated apparatus. For

this reason, no more than qualitative instructions can be furnished on this point. In general, the voltage may be increased or decreased by means available to those skilled in the art. For instance, assuming that a vacuum tube oscillator is employed for supplying the power, the voltage may be increased by increasing the plate voltage of the oscillator; or by tightening the coupling between the plate and grid circuits of the oscillator; or by tightening the coupling between the plate circuit and the circuit supplying current to the lapped filaments; or by adjusting the length of power leads to the welding apparatus to coincide with maxima or less than maxima, of the resonance pattern thereof. The maximum possible voltage will be that at which are discharge of the electric current occurs. Below this maximum voltage, the voltage should be adjusted to a value such as to secure a weld within a certain optimum time, more particularly set forth hereinafter; if, at any particular voltage, the formation of a weld requires a longer period than the optimum, the voltage should be increased; conversely, if a weld is formed in less than the optimum time, the voltage should be decreased.

The time during which the monofilaments are subjected to the electric fleld is quite critical. In general, the field should not be applied for a longer duration of time than is necessary to effect the weld, as the strength of the weld is deteriorated beyond this point. This duration is an inverse function of voltage and of frequency of applied field; with any selected frequency, the voltage should be adjusted as above described to secure welding in the optimum time for that frequency. These optimum times at various frequencies are:

Table I Optimum Frequency, megacycles time seconds i it so As above noted, the monfilaments should be held together with a definite pressure during welding, which pressure should preferably be between about 3.0 lb. and about 6.0 lb. per linear inch of monofilament interface to be welded together. Higher and lower pressures may be used, but will result in inferior welds. This optimum pressure does not vary significantly with customary sizes of monofilaments.

A Wide variety of thermoplastic monofilaments may be spliced together by means of the process of this invention, the principal criterion being that the material of which the monofilament is made shall be sufliciently thermoplastic so that monofilaments thereof will heat seal, i. e., will adhere to one another when heated and pressed together. Suitable monofilaments will thus be seen to include, for instance, the oriented-crystalline monofilaments produced from polymers of vinylidene chloride and copolymers thereof with minor proportions of other unsaturated compounds copolymerizable therewith such as vinyl chloride, vinyl acetate, vinyl ethers, styrene, acrylic esters and nitriles, etc., examples of commercial products of this type being Velon or Saran products respectively of The Firestone Tire & Rubber Company and of The Dow Chemical Company. Another important class of thermoplastic monofilaments which may be spliced in accordance with this invention are the nylon monofilaments, which are oriented-crystalline high molecular polyamides such as condensation products of hexamethylene diamine with adipic acid, or condensates of w-amino caproic acid, etc. Other monofilaments suitable for use in this invention include those comprising polymers of vinyl chloride and copolymers thereof with minor proportions of other unsaturated compounds copolymerizable therewith, such as vinyl acetate, vinylidene chloride, acrylic esters and nitriles, styrene, vinyl ethers and the like, an example of this type of fiber being marketed under the name of Vinyon by the Carbide and Carbon Chemicals Corporation; or cellulose derivatives such as cellulose acetate, ethyl cellulose, benzyl cellulose, etc. By the term monofilament it is intended to designate any wire-like, solid integral plastic strands of substantial cross sectional area (say 25-400 circular mils cross sectional area) as distingulshed from conventional textile threads 7 composed of a number of very fine filaments held together by virtue of their twist. By the term "monofllament it is also intended to include conventional textile threads which have been impregnated and coated with plastic composition so as to provide a, substantially solid monofllament of plastic composition reinforced by the fine filaments of the textile thread, an example of such a product being Textron a, plastic-coated thread manufactured by the Freydberg Brothers-Strauss, Inc.

As above briefly noted, a considerably dificulty arises in the practice of this invention by virtue of the tendency of the electric currents to arc around the filaments, especially along the surfaces of any insulating materials used to support the monofilaments in welding position. Such arcing quickly destroys the insulating materials. Thus trouble may be minimized by keeping the surfaces of the insulating materials scrupulously clean. A more effective method, somewhat at variance with the foregoing recommendation for cleanliness, is to lightly coat the surfaces of the insulators with an oil, preferably of the paraffin type.

Apparatus so coated has operated for days in an entirely satisfactory manner, while identical apparatus, operating under the same conditions without the oil coating, was destroyed in a few hours. The reasons for this phenomenon are obscure, and it is tentatively suggested that the on film provides a more uniform and less abrupt electrical gradient through the surface of the insulation material. This technique is particularly satisfactory with ceramic insulating materials such as glass, porcelain, alumina and the like.

With the foregoing general discussion in mind, there will now be described specific forms of apparatus for carrying out the process of this invention. The apparatus is shown in the accompanying drawings in which:

Fig. 1 shows a perspective view of a press assembly arranged to weld plastic monofilaments according to this invention.

Fig. 2 shows an enlarged view of the spliced filaments before trimming.

Fig. 3 shows an enlarged view of the spliced filaments after trimming.

Fig. 4 shows an enlarged side view of the electrode assemblies in open position, together with the mode of inserting the monofilaments to be spliced.

Fig. 5 is an enlarged section on the line 5-5 of Fig. 4.

Fig. 6 is a section on the line 6-6 of Fig. 4.

Fig. 7 is an enlarged portion of Fig. 6, with the electrodes in closed position.

Fig. 8 is a wiring diagram of a high frequencygenerator for use in this invention.

Figs. 9 and 10 show an alternative electrode assembly.

Figs. 11-14 show an electrode assembly similar to that of Fig. 4, together with means for automatically trimming the filaments after welding:

in these figures,

Fig. 11 is a front view of a lower electrode assembly similar to that of Fig. 4, with means for trimming the spliced filaments.

Fig. 12 is a top view of the assembly of Fig. 11.

Figs. 13 and 14 are respectively side and end views of cutting chisels used in Figs. 11 and 12.

Fig. 15 is an enlarged fragmentary top view of a warp of monofilaments spliced in accordance with this invention, together with the adjacent portion of the fabric into which the warp is being Synopsis of entire apparatus, Figs. 1-8

Referring to the drawings, and first to Fig. 1, there is shown a kick press 28 having a lower stationary jaw 22 carrying a lower electrode assembly 24 adapted to hold, in overlapped rela tion, the ends 23, 25 of the monofilarnents 2i and 28 which are to be spliced (see Figs. 4 and 5). The main lengths of the monofilaments are wound upon the rolls 2? and 29, and it will be noted that the loose ends 23, 25 of these rolls are allowed to extend beyond the welding apparatus. The movable upper jaw 30 of the press carries an upper electrode assembly 32 and is so arranged that, when the pedal 34 is depressed, the upper jaw 38 descends and carries the upper electrode assem bly 32 down into mating en agement with the lower electrode assembly it. a high frequency electric current from the vacuum tube oscillator 36 is then passed from the upper to the lower electrode assemblies through the lapped monofilaments 26 and 23, causing them to become heated and welded together along the zone 3? as shown in Fig. 2.

It will be noted (Fig. 2) the spliced nionoilia ments have excess ends 23, since t is inconvenient, in practice, to insert the rnonorllan'ients so that their ends do not extend beyond the electrodes. These loose ends may be snipped off as indicated in Fig. 3 by means of scissors or special cutters, more particularly described hereinbelow in connection with Fig. ll.

Figs. i5 and i5 illustrate the desirable features, both in. the process of weaving, and in the finished fabric, of rnonofilaments spliced together in accordance with this invention. in these figures there is shown a portion of a warp of monofilamerits 39 passing through. the dents 53 of the reed of a loom (not shown) on which the warp 39 is being woven into a fabric d5. Certain of the monofilaments contain welded splices ll, it identical with that shown in Fig. 3. it will be seen that the splice ll passes very smoothly be= tween the dents 4?, whereas a lmot would be repeatedly abraded and disturbed by the reciprocation of the dents 53; in practice, it has been found that knotsso situated frequently come untied, with consequent interruption to production. Likewise it will be seen that the spliced portion 19 disturbs the continuity of the fabric db very little, whereas a conventional knot would be most unsightly.

The-lower electrode assembly 24 This assembly is more particularly shown in Figs. 4-7 as comprising a sheet metal electrode 38 sandwiched between two glass plates 4!: (Pyrex #774, manufactured by the Corning Glass Works) which in turn are grasped between two blocks d2 of insulating material (Melmac #592, manufactured by the American Cyanamid Company) which are held together by bolts 44 passing therethrough to nuts 46. The assembly is adjustably clamped to the lower press jaw 22 by means of screws 48 extending through a yoke 50 and into the blocks 42.

The thickness of the electrode 38 is approximately the same as the diameter of the monofilamerits, and the electrode terminates short of the upper edges of the glass plates 48, so as to define therewith a slot 4| into which the monofllaments 26 and 28 may be inserted in superposed, lapped relation as shown in Figs. 4-6.

The upper working edge 52 of the electrode is relieved at 54 and 56, so that the welding current and pressure are applied only along the land portion from 58 to 68. Portions 58 and 60 are rounded to avoid concentration of electrical stress.

The electrode also 'has a lug 62 extending from between the plates 40 for the attachment to a wire 64 connected to the oscillator 35.

The upper electrode assemblybz This assembly more particularly comprises a sheet metal electrode 58 sandwiched between two glass plates 6'! (Pyrex #774) which in turn are grasped between two blocks 68 of insulating material and held together by bolts 59 passing therethrough to nuts it. The assembly is adjusta'oiy clamped to the upper press jaw 38 by means of screws it extending through the yoke '52 and into the blocks Bil. The lower working edge iii of the electrode extends downward from between the plates ill, and the upper and lower electrode assemblies 2t and are so aligned that, when the upper press jaw moves down-- wardly, the working edge enters the slot it and compresses the superposed, lapped monofilamerits t6, together and against the land portion from 53 to of the lower electrode 38. This is shown in dashed outline in 4;, and also in full lines in Fig. l.

Complementarily to the lower electrode 38, the working edge oi the electrode "36 relieved at M and so that only the intermediate laud. portion from it to 8d engages the filament; this land portion it, of the upper electrode is dis posed opposite "he land portion to of the lower electrode as shown. in Figs. i, 5 and i so that the welding pressure and current are confined to the weld zone Similarly to the lower electrode 38, the upper electrode rounded at "58 and B8, and has a lug extending from between the blocks Eli for connection to a wire 8-". leading to the oscillator Kick Press Mechanism Any conventional press mechanism may be used which will move the upper electrode assembly 32 into engagement with the lower electrode assembly it. However since, as will appear from data hereinafter detailed, best results are obtained when the pressure of the electrodes upon the filaments is precisely regulated, the kick press mechanism should preferably include means for regulating the electrode pressure regardless of the pressure exerted by the operator upon the pedal In the specific mechanism shown, the press comprises a. master arm 34 pivoted to the press standard 86 at 38 and connected by positive mechanical linkage 31 to the pedal 34 so that depressing the latter will positively rock the master arm 84 in counterclockwise sense in the drawing upon its pivot 88. The upper jaw 38 of the press is freely pivoted at 98 upon the standard 86, and a spring buffer Qi s interposed between the upper jaw and the master arm 84, so that the latter, when depressed by actuation of the pedal 34, thrusts the upper jaw and electrode assembly 32 carried thereby downward into mating engagement with the lower electrode assembly 24. The limit of travel of the master arm 84 is set so as not to completely compress the spring buffer 9|, so that the maximum pressure exerted by the electrodes upon the monofliaments will be governed solely of the pressure exerted by the operator upon the pedal 34.

through insulated wires H5 threaded through the copper tubes I I and connected to those ends of the filaments of the tubes I08 to which the copper tubes H0 are not connected. Return of Aslotted-link lost motion connection 92 is-proheating current is via wires H2, copper tubes vided between the master arm 64 and the upper H0, and wires 6. The filament-grid tuning jaw 30, whereby the clockwise rocking of the circuit 0 is completed by a conducting bridge master arm is permitted to compress the buffer H0 across the tubes H0 which is slidable along 9|, but when the master arm rocks counterthe tubes to tune the circuit. The grids of the clockwise again, the lost motion is taken up, and in tubes I08 are connected together and to the the upper Jaw and electrode assembly are recenter tap of the filament transformer Ill tracted from the lower jaw and electrode assemthrough a leak resistor I I1. bly, permitting removal of the welded filaments. The plate circuit comprises a connection H6 The oscillator 36 from the negative terminal I06 of the rectifier u to the center tap of the filament transformer y vacuum tube oscillator may be used which 4. The plates of the tubes I00 are connected is capable of gen r r n f f quencies to a, tank circuit comprising a, pair of O. D. on the order of -250 megacycles, and of power copper tubes I20 12" long spaced apart and requisite (usually drawing about 100-1000 watts provided with a sliding conducting bridge I22 plate power input) to efiect a weld within the n for tuning. Return to the positive terminal I01 desired time. A suitable oscillator is shown in is via radio frequency choke I26 (20 mh.) and Fig. 8 as comprising a supply line 04 providing wire I30. alternating current power: a full wave rectifier, High frequency power is abstracted from the 96 drawing its plate po er om the line through plate circuit by means of a hair pin loop I32 a self-resetting timing switch 98 and a limit $5 of A copper tubing, mounted so as to be s tc Placed on the fioor I02 beneath the movable into or out of the field of the tank cirp dal 34 so as to close circuit when the pedal is cuit I20, I22 to increase or decrease the voltage depressed. The filaments of the tubes in the applied to the electrodes 38, 66. rectifiers are supplied independently of he switches 98, I00 through wires I04. The recti- Optimum conditions of operation fier has a rated output at its terminal I06, I01 A series of welds were made between filaments of 2000 volts at ma. D. C. In operation, when with the apparatus of Fig. 1, using various types the operator depresses the pedal 34, it engages of plastic monofilaments at various frequencies: the switch In at the limit of its travel, thereby various times of welding and correlated applied supplying plate power to the rectifier so that a voltages: and various degrees of pressure on the rectified high voltage becomes available at the electrodes as set forth herewith in Table 11. output terminals I06 and I01. The timing From a consideration of the table, it will be apswiteh I00 is arranged to automatically break parent that best results are obtained with prescircuit at the end of the interval for which it is sures of from about 3.0 lb. to about 6.0 lb. per set, and to reclose itself in readiness for the next 0 linear inch (Table II, items Nos. 12-15), and cycle of operations. that the optimum times welding follow the The oscillator proper more particularly inschedule of Table I (see Table II, items Nos. 2 eludes two T- tubes I08, having a filamentand 10).

Table II Filament ressue T u poun 5 ens B as m a e Material mils I filament) Saran 15 25 a 4 2.6

a 4 3.3 1 4 3.3 s 4 at e 4 2.8 Saran 15 50 1o 4 2.2 15 4 1.6

Saran 15 40 4 4.0

Saran 10 175 25 4 2.1 Nylon 15 175 25 4 9.0 18 Tetron 18 175 25 4 6.0

1 Olive drab formulation of vinylidene chloride resin, oriented after extrusion.

Unpigmented nylon filament, I Plastic coated fl oriented after extrusion. aments manufactured by Freydberg Bros-Strauss Inc.

Modified electrode assembly (Figs. 9 and 10) A modified form of the welding electrode arrangement is shown in Figs. 9 and 10 as comprising identical upper and lower electrode assemblies I36, I38 secured respectively to the upper and lower jaws 30, 22 of the kick press 20. Each electrode assembly comprises a sheet metal electrode I31 sandwiched between a pair of blocks I39 of insulating material, which blocks are compressed together by means 01 a screw I40 passing therethrough into nuts I. Each electrode assembly is secured to its corresponding press jaw by means of screws I42 passing through yokes I43 and into the insulating blocks I39. Each electrode I31 is slightly wider than the monofilaments 26, 28 to be welded, and the working surface M4 thereof is set flush with the blocks I38, forming therewith a substantially plane surface I56. A groove I48 is cut longitudinally of each electrode I36 to a depth of about half the diameter of the monofilaments 26, ml, so that they may be cradled therein as shown in Figs. 9 and ill. The upper and lower electrode assemblies are aligned, so that, upon closure of the jaws of the press, the monofllaments 25, 2s cradled in the grooves H8 are pressed together in overlapping relation. A high frequency current is then passed between the electrodes i35, effecting a weld of the moncfilaments.

Various means may be employed for inserting and retaining the monofilaments in the grooves One simple means comprises a pair of notches, lell and till cut out of each end of the electrode assembly with their apexes coinciding with the groove old. A pair of spring clips lcil are secured to the assembly by the screws ltd and have ears ltd, Q55 yieldably embracing the ends of the electrode assembly. In use, to insert a monorllan'lent such as Elli into the groove in cradled position, one end of the filament is slipped under the ear l54; the filament is drawn over the notch tail; over the groove MB; down into the notch till; and under the ear i256. The filament is held taut during these operations, so the notches ltil, lfil guide the filament into the groove hill. The spring ears 555, 156 hold the filaments taut in the groove M8 during the welding operations.

Trimming knife assembly Figs. ll-ld show a lower electrode assembly similar to the electrode assembly 2d of Figs. 1-6 and designed to replace the same, and being provided with means for cutting on the excess ends of the monofilaments 326, 323 after the conclusion. of the welding operation. The assembly more particularly comprises a sheet metal electrode glass plates 340, and insulating blocks 3 42 all similarly constructed and arranged upon the lower jaw 22 of the press as are the corresponding elements 38, 40 and 42 of Fig. 4. (To indicate parts in Figs. 11-14 corresponding to those in Figs. he, the reference characters in Figs. 1-6 hav been increased by 300; thus 38 in Fig. 4 is the same element as 338 in Fig. 13, and so on.) The insulating blocks 342 are of considerable width and have slideways 444 pierced therethrough, in which chisels 448 and 441 reciprocate for the purpose of cutting off the excess ends 323, 325 of the monofilaments.

The chisel M8 comprises a horizontally directed dividing portion 448 and an upwardly directed cutting portion 450, its edge being aligned with the end 452 of the welded zone or" the filament. The forward end of the dividing portion 448 is ground off to provide a slanting separating blade 454 extending between the monofilament 328 and the excess end 323. The function of thisseparating portion is to pry the monofllament and excess end apart as the knife 6 is pushed toward the monofllaments. The forward end of the cutting portion 450 is ground to a cutting edge 456. In operation, assuming that a weld has just been completed between the monofilaments, the chisel 448 is pushed in its slideway, toward the monofilaments. The separating blade 454 enters between the monofilaments and forces them apart. Continued motion of the chisel brings the cutting edge 456 into engagement with that portion of the loose end 323 immediately adjacent the welded Zone 33'! whereby the loose end 323 is clipped off.

The rear portion 458 of the chisel is square in cross section, and the corresponding rear portion of the slideway $44 is likewise square in cross section and snugly embraces the square portion 458 of the chisel, so as to permit the chisel to be reciprocated longitudinally while preventing rotation thereof about longitudinal axis-which rotation, if not restrained, would spoil the register of the chisel with the filaments. The forward end of the slideway 54% is enlarged to form a pocket see into which the chisel is withdrawn when not in action. The blades we, abut rear walls of the pocket loll so as to limit the retraction of the chisel. The exterior and of the chisel provided with a knob which may be pressed to actuate the chisel to trim on the excess end A helical compression spring tilt surrounds the chisel between the knob E62 and the block M2 to retract the chisel after such actuation.

The chisel Ml! is arranged and constructed 1 identically to the chisel are, but is positioned to cut on the loose en whereby they me effect the cutting a pneumatic or electrical means may he to eilect this movement automatically u on the conclusion of the welding operation.

From a consideration-of the foregoing description, it will be seen that this invention provides a novel method and apparatus for efiecting splices between thermoplastic rnonofilaments. The apparatus and procedure involved are simple and inexpensive, and the welded filaments are strongly and permanently united.

What is claimed is:

1. Process which comprises overlapping, in. parallel relationship, the ends of two lengths of thermoplastic monofilament, pressing said monofila :nents together with a force of from about 31? to about 6.0 pounds per linear inch of overlapp d monofilaments and subjecting the overlapped filaments to a high frequency electrostatic field, said field having a frequency of from about to 250 megacycles and having an intensity such that a weld is effected between the filaments within a period of time which is a function of the frequency employed, substantially in accordance with the table:

eclprocated to Frequency Employed (megacycles) i gggs pounds per linear inch of overlapped monofilaments and subjecting the overlapped filaments to a high frequency electrostatic field, said field having a frequency of from about 150 to about 250 megacycles and having an intensity such that a weld is efl'ected between the filaments within a period of time which is a function oi. the frequency employed, substantially in accordance with the table:

Frequency Employed (megacycles) mgg 3. Process which comprises overlapping, in parallel relationship, the ends of two lengths of nylon monofilament, pressing said monofiiaments together with a force of from about 3.0 to about 6.0 pounds per linear inch of overlapped monofilaments and subjecting the overlapped filaments to a high frequency electrostatic field, said field having a frequency of from about 159 to about 250 megacycles and having an intensity such that a weld is eifected between the filaments within a period of time which is a function oi 12 the frequency employed, substantially in accordance with the table:

. Frequency Employed (megaoycles) T135213? no i 15 115 25 2m 30 FRANK J. ano'rmq.

WILLIAM J. NANFEIDI.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PA Number Name Date 2,279,299 Cavanaugh Apr. 14, 1942 20 2,298,676 Camp Oct. 13, 1942 2,335,159 Salfisberg Nov. 23, 1943 2,402,699 Brabander June 25, 1946 2,435,467 Spencer Feb. 3, 1948 u 01' REFERENCES Hoylcr: Electronic Sewing Machine, reprint from the August 1943 issue of Electronics.

Certificate of Correction Patent No. 2,514,197 July 4, 1950 FRANK J. GROTEN ET AL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Column 4, line 12, for considerably read considerable; column 7, line 31, for 30 ma. D. O. read 300 ma. D. 0.; line 33, for switch 10 read switch 100 and that the said Letters Patent should be read as corrected above, so that t e same may conform to the record of the case in the Patent Office.

Signed and sealed this 13th day of March, A, D. 1951.

THOMAS F. MURPHY,

Assistant Gommz'ssz'oner of Patents.

Certificate of Correction Patent N 0. 2,514,197

July 4, 1950 FRANK J. GROTEN ET AL.

It is hereby certified that error appears in the rinted specification of the above numbered patent requiring correction as to lows:

Column 4, line 12, for considerably read considerable; column 7 line 31, for 30 ma. D. C. read 300 ma. D. 0.; line 33, for switch 10 read switch 100;

and that the said Letters Patent should be read as corrected above, so that t e same may conform to the record of the case in the Patent Ofi'ice.

Signed and sealed this 13th day of March, A D. 1951.

THOMAS F. MURPHY,

Assistant Uommz'ssz'oner of Patents. 

1. PROCESS WHICH COMPRISES OVERLAPPING, IN PARALLEL RELATIONSHIP, THE ENDS OF TWO LENGTHS OF THERMOPLASTIC MONOFILAMENT, PRESSING SAID MONOFILAMENTS TOGETHER WITH A FORCE OF FROM ABOUT 3.0 TO ABOUT 6.0 POUNDS PER LINEAR INCH OF OVERLAPPED MONOFILAMENTS AND SUBJECTING THE OVERLAPPED FILAMENTS TO A HIGH FREQUENCY ELECTROSTATIC FIELD, SAID FIELD HAVING A FREQUENCY OF FROM ABOUT 150 TO 250 MEGACYCLES AND HAVING AN INTENSITY SUCH THAT A WELD IS EFFECTED BETWEEN THE FILAMENTS WITHIN A PERIOD OF TIME WHICH IS A FUNCTION OF THE FREQUENCY EMPLOYED, SUBSTANTIALLY IN ACCORDANCE WITH THE TABLE: 